Pre workout

After putting an I'm in on the pre workout challenge,  I realized I didn't know what a pre workout was. I started researching and found it is a supplement that may provide energy for workout plus mental focus. I started looking at websites and started to read about the pros and cons. The pros are potentially getting better focus and energy while doing a workout.  I remember when I was 16 I wanted more muscle and in addition to workouts with weights I also took some sort of workout powder from (u think) GNC. I remember great hope as a friend gained a lot of muscle mass. The reality for me was not getting any extra muscle that I can remember.  I researched the cons and what I read is that most of the time there is no danger but also it doesn't appear to help either. Therefore,  I decided against trying any current product.